Purpose: :
The human retinal pigment epithelium (hRPE) is a monolayer ofmitotically inactive cells that lies just anterior to the choroidvascular layer of the posterior retina. Proliferation of hRPEmay lead to retinal neovascularization in patients with diabetes.Research shows that a balance between two endogenous growthfactors, vascular endothelial growth factor (VEGF) and pigmentepithelium derived growth factor (PEDF), is required to maintaina quiescent hRPE. We have investigated whether PEDF modulatesintracellular synthesis of VEGF-R2, one of the two known VEGFreceptors.

Methods: :
hRPE cultures were established from eyes obtained from the MichiganEye Bank. Responsiveness to biological stimuli was ascertainedby measuring proliferation after cells were treated with a knownmitogen, fetal bovine serum (FBS). To measure intracellularVEGF- R2 synthesis, hRPE was labeled with 14-C-methionine aftertreatment with control media, glucose, PEDF, or combinationsof the three. Cells were immunoprecipitated with anti-VEGF-R2antibody and protein A, and radioactivity was measured witha scintillation counter. In separate experiments, hRPE was treatedwith the same reagents then fluorescently labeled with anti-VEGF-R2antibody and DAPI nuclear stain.